Recently, the display devices using liquid crystal (hereinafter, referred to as display) is spreading at conspicuous pace. The display of this type is low in power consumption and improved in saving space, in comparison with a CRT display. Accordingly, it is important to make use of the merits of such a display and produce a display that is lower in power consumption and improved in saving space.
FIG. 15 is a block diagram of a system for providing display on a display device by a TFT display. This system is configured with a digital interface 100 and a TFT liquid crystal display panel 101. The digital interface 100 is configured, at least, with a CPU 100A, a RAM 100B, a frame memory 100C and an LCD controller 100D. The CPU 100A is operation control means for transmitting display data while exchanging data with the RAM 100B as a general-purpose memory. Because this RAM 100B is not especially used merely as a memory for display, there is newly a need of a memory for storing the data for display. That is the frame memory 100C. The frame memory 100C temporarily stores the display data in an amount of one screen of the liquid crystal panel 101C (hereinafter, the data in an amount of one pixel is given display data, and each binary signal constituting the display data is referred to as an image signal). The LCD controller 100D carries out transmission control of display data in order to display, in timing, each of display data stored in the frame memory 100C in a display position on the liquid crystal panel 101C. Herein, for a CRT there is a necessity to transmit display data through conversion into analog data. It is however considered that the interface of the liquid crystal display is compatible with digital data, and herein the display data is transmitted by an image signal as digital data.
Meanwhile, the TFT liquid crystal display panel 101 in configured with a scanning line driver 101A, a digital data driver 101B and a liquid crystal panel 101C. The scanning line driver 101A carries out display control in a scanning line (row) direction on the basis of the timing data transmitted from the LCD controller 100D. The digital data driver 101B is allowed to receive and process the digital-data image signal. The digital data driver 101B carries out display control in a data-line (column) direction on the basis of the timing data transmitted from the LCD controller 100D. On that occasion, it also controls the tonal levels of display. The liquid crystal panel 101C is a panel having TFTs (Thin Film Transistors) to effect display under the control of the scanning line driver 101A and digital data driver 101B.
Such a system requires a frame memory 100C for temporarily store the display data in an amount of all over the screen. Furthermore, an LCD controller 100D is required to transmit an image signal for the display data to the digital data driver 101B.
Consequently, the system overall requires many of means thus increasing its scale. Moreover, the reduction of consumed power cannot be achieved because of a great deal of the amount of transmitting such data and large power consumption as a result thereof.
Therefore, it is a problem of the present invention to provide a display device capable of achieving space saving and consumed power reduction for the system overall.